Mammoth Cave National Park
By: Mike Wallin

 
While cruising on Interstate 65 near west central Kentucky
geologists start to see some interesting things with the road cuts. These
road cuts along the highway show exposures of layered grayish rocks.
These Layers of grayish rock the person sees shows openings in the stone.
This is strong beginning evidence of one of the best examples of karst
topography in the world. Karst topography is an erosion process that uses
rain water and carbon dioxide gas form carbonic acid. The carbonic acid
breaks down to make a hydrogen ion solution. Then the hydrogen solution
and calcium carbonate (limestone) forms a calcium ion and a bicarbonate
ion. Basically this breaks down the limestone and turns it into a
solution causing Karst features called a cave. In Kentucky, on Interstate
65, is where the biggest cave system in the world is located(Harris,145).
This cave system is called the Mammoth Cave National Park. This report 
will go over a brief history, the amazing features found in the park, and the 
stratigraphy of this area.

Mammoth cave has been through many changes over the time it has
been in existence. About 3000-4000 years ago Indians used the cave for
shelter and minerals used in their medicines. Also in Mammoth Cave two
Indian mummies were found in the cave. Later in Mammoth Cave history
during the War of 1812 some of its passages were mined for saltpeter a
main ingredient in gunpowder. Mammoth Cave was authorized as a natural
park in the year of 1926. Lastly a cave research foundation was founded
in 1957(Harris148).

Many interesting karst features can be seen in Mammoth Cave. Click here to 
see an illustration shows karst topography features of Mammoth Cave, this 
illstration is from the National Park service. These 
cave features are called speleothems. In Mammoth Cave, many
speleothems are seen such as flowstone, stalactites, stalagmites, and
columns. Flowstone is made when cave water runs on a wall of the cave and
forms a blanket looking thing. Another feature is stalactites these are
icicle-shaped rock formation on top of the roof of the cave. Next are
stalagmites these are poles of rock formed on the ground. Also columns
are formed this is when stalagmites and stalactites converge into one
single formation resembling a column. Other speleothems that are in
Mammoth Cave include helictites, gypsum flowers, marbilite, and epsomite.
In the time of 350 million years ago the continent of North America was
farther south than it is today. Kentucky was about 10 degrees south of
the equator. A shallow sea covered this entire area. Many organisms
lived in this warm shallow continental sea. These organisms lived and
died in this area. The dead bodies of the organisms accumulated and it
started to form the huge layers of limestone.

 Mammoth Cave is placed within three limestone layersof the stratigraphy column: St. Louis, Ste.
Genevieve, and the Girkin Formation.

The oldest limestone layer Mammoth Cave occupies is the St. Louis
limestone. The limestone layer is about 200 feet thick and Mammoth Cave
is located only in the upper part of the layer.

Next is the Ste. Genevieve limestone layer. Mammoth Cave occupies the
entire thickness of this 110 feet thick layer.

The last and youngest limestone layer is the Girkin Formation. Mammoth
Cave also occupies this formation in the 135 feet thick layer.

Above these thick limestone layers lie the younger rock units of the
Chester Series. The Chester series is a thick cap layer. This layer is
mostly composed of sandstone. This sandstone is covered by a
disconformity. Next a layer of Pennsylvanian conglomerates is found.
This layer is only found on the northern part of the park.

Over all the rock layers has about less than a degree dip. The cave system
started to form in the late Paleozoic. At this time small cracks and
fractures started to widen and become very small caves. Next the caves
started to become wider and longer. The upper most levels formed 30 to 5
million years ago. The development of the lower levels of Mammoth Cave
started during the Pleistocene and is still continuing today.

Mammoth Cave National Park is one of the best examples of karst
topography in the world. This national park is very useful to the
geologists because it is a real working laboratory. Mammoth Cave has a
rich history, many fine examples of karst features, and great stratigraphy
of the area.
 
Refrences
 Harris G.A. and Tuttle E,Geology of National Parks, Kendall/Hunt Puplishing Company, 1990, P.145- 158